Display apparatus

ABSTRACT

A display apparatus includes a substrate, a light-emitting diode (“LED”) provided above the substrate, an insulating layer provided above the LED, and a wire grid polarizer (“WGP”) provided above the insulating layer.

This application is a continuation of U.S. patent application Ser. No.15/484,456, filed on Apr. 11, 2017, which claims priority to KoreanPatent Application No. 10-2016-0044263, filed on Apr. 11, 2016, and allthe benefits accruing therefrom under 35 U.S.C. § 119, the content ofwhich in its entirety is herein incorporated by reference.

BACKGROUND 1. Field

One or more exemplary embodiments relate to display apparatuses, andmore particularly, to a display apparatus having improved reliabilityand visibility.

2. Description of the Related Art

A light-emitting diode (“LED”) is a device that converts an electricsignal into a form of light, such as an infrared light or visible light,by characteristics of a compound semiconductor. Areas of use of the LEDare gradually increasing, and the LED is extensively used in a varietyof fields of electronic devices from a miniature hand-held electronicdevice to a large display apparatus, such as a home appliance, a remotecontroller, an electronic display board, and an automation device.

SUMMARY

When a conventional display apparatus uses a light emitting deviceincluding an organic emission material, not only does the organicemission material have a characteristic of being vulnerable to anexternal environment but also visibility of the conventional displayapparatus deteriorates due to light reflected from outside.

In order to solve several problems including the aforementioned problem,one or more exemplary embodiments include a display apparatus havingimproved reliability and visibility.

Additional exemplary embodiments will be set forth in part in thedescription which follows and, in part, will be apparent from thedescription, or may be learned by practice of the presented exemplaryembodiments.

According to one or more exemplary embodiments, a display apparatusincludes a substrate, a light-emitting diode (“LED”) provided above thesubstrate, an insulating layer provided above the LED, and a wire gridpolarizer (“WGP”) provided above the insulating layer.

In an exemplary embodiment, the insulating layer may expose an uppersurface of the LED.

In an exemplary embodiment, the WGP may contact the upper surface of theLED.

In an exemplary embodiment, a height of an upper surface of theinsulating layer may be equal to or less than a height of the uppersurface of the LED with reference to the substrate.

In an exemplary embodiment, an opening that exposes the upper surface ofthe LED may be defined in the insulating layer.

In an exemplary embodiment, the LED may include a p-n diode, a firstcontact electrode, and a second contact electrode, where the firstcontact electrode and the second contact electrode are provided in theupper surface of the LED.

In an exemplary embodiment, the display apparatus may further include afirst electrode provided above the substrate, and a reflection layerinterposed between the LED and the first electrode.

In an exemplary embodiment, the display apparatus may further include apixel defining layer including a concave region that exposes a centralportion of the first electrode, where the reflection layer is providedabove the concave region.

In an exemplary embodiment, the display apparatus may further include apixel protection layer provided above the LED.

In an exemplary embodiment, the pixel protection layer may cover thereflection layer.

In an exemplary embodiment, the pixel protection layer may furtherinclude fine particles.

In an exemplary embodiment, the display apparatus may further include asecond electrode provided above the pixel protection layer, where anopening that exposes at least a part of the upper surface of the LED isdefined in the pixel protection layer, and where the second electrodecontacts at least a part of the upper surface of the LED through theopening.

In an exemplary embodiment, the display apparatus may further include afirst electrode and a second electrode provided above a same layer ofthe substrate, where the LED is electrically connected to the firstelectrode and the second electrode.

In an exemplary embodiment, the LED may include an upper surface, alower surface, and a side surface connecting the upper surface and thelower surface and further includes a metal layer provided to cover theside surface of the LED.

In an exemplary embodiment, the LED may include a p-n diode, a firstcontact electrode, and a second contact electrode, where the firstcontact electrode and the second contact electrode are provided in asame side.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other exemplary embodiments will become apparent and morereadily appreciated from the following description of the exemplaryembodiments, taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a plan view schematically illustrating an exemplary embodimentof a display apparatus according to the invention;

FIG. 2 is a schematic cross-sectional view taken along line X-X′ of FIG.1;

FIG. 3 is a cross-sectional view schematically illustrating anotherexemplary embodiment of a display apparatus according to the invention;

FIG. 4 is a cross-sectional view schematically illustrating anotherexemplary embodiment of a display apparatus according to the invention;and

FIG. 5 is a cross-sectional view schematically illustrating anotherexemplary embodiment of a display apparatus according to the invention.

DETAILED DESCRIPTION

As the invention allows for various changes and numerous exemplaryembodiments, exemplary embodiments will be illustrated in the drawingsand described in detail in the written description. Advantages andfeatures of one or more exemplary embodiments and methods ofaccomplishing the same may be understood more readily by reference tothe following detailed description of the one or more exemplaryembodiments and the accompanying drawings. The invention may, however,be embodied in many different forms and should not be construed as beinglimited to the one or more exemplary embodiments set forth herein.

Reference will now be made in detail to exemplary embodiments, examplesof which are illustrated in the accompanying drawings. Like referencenumerals in the drawings denote like elements, and a repeateddescription thereof will be omitted.

While such terms as “first” and “second” may be used to describe variouscomponents, such components must not be limited to the above terms. Theabove terms are used only to distinguish one component from another. Thesingular forms “a,” “an,” and “the” used herein are intended to includethe plural forms as well, unless the context clearly indicatesotherwise.

It will be understood that terms such as “include,” “comprise,” and“have” used herein specify the presence of stated features orcomponents, but do not preclude the presence or addition of one or moreother features or components. It will be further understood that when alayer, region, or component is referred to as being “on” another layer,region, or component, it can be directly or indirectly on the otherlayer, region, or component. That is, for example, intervening layers,regions, or components may be present.

Furthermore, relative terms, such as “lower” or “bottom” and “upper” or“top,” may be used herein to describe one element's relationship toanother element as illustrated in the Figures. It will be understoodthat relative terms are intended to encompass different orientations ofthe device in addition to the orientation depicted in the Figures. In anexemplary embodiment, when the device in one of the figures is turnedover, elements described as being on the “lower” side of other elementswould then be oriented on “upper” sides of the other elements. Theexemplary term “lower,” can therefore, encompasses both an orientationof “lower” and “upper,” depending on the particular orientation of thefigure. Similarly, when the device in one of the figures is turned over,elements described as “below” or “beneath” other elements would then beoriented “above” the other elements. The exemplary terms “below” or“beneath” can, therefore, encompass both an orientation of above andbelow.

“About” or “approximately” as used herein is inclusive of the statedvalue and means within an acceptable range of deviation for theparticular value as determined by one of ordinary skill in the art,considering the measurement in question and the error associated withmeasurement of the particular quantity (i.e., the limitations of themeasurement system). For example, “about” can mean within one or morestandard deviations, or within ±30%, 20%, 10%, 5% of the stated value.

Sizes of components in the drawings may be exaggerated for convenienceof explanation. In other words, since sizes and thicknesses ofcomponents in the drawings are arbitrarily illustrated for convenienceof explanation, exemplary embodiments are not limited thereto.

An x-axis, a y-axis and a z-axis are not limited to three axes of arectangular coordinate system and may be interpreted in a broader sense.For example, the x-axis, the y-axis, and the z-axis may be perpendicularto one another or may represent different directions that are notperpendicular to one another.

When an exemplary embodiment may be implemented differently, a specificprocess order may be performed differently from the described order. Forexample, two consecutively described processes may be performedsubstantially at the same time or performed in an order opposite to thedescribed order. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and theinvention, and will not be interpreted in an idealized or overly formalsense unless expressly so defined herein.

Exemplary embodiments are described herein with reference to crosssection illustrations that are schematic illustrations of idealizedembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, embodiments described herein should not beconstrued as limited to the particular shapes of regions as illustratedherein but are to include deviations in shapes that result, for example,from manufacturing. In an exemplary embodiment, a region illustrated ordescribed as flat may, typically, have rough and/or nonlinear features.Moreover, sharp angles that are illustrated may be rounded. Thus, theregions illustrated in the figures are schematic in nature and theirshapes are not intended to illustrate the precise shape of a region andare not intended to limit the scope of the claims.

FIG. 1 is a plan view schematically illustrating a display apparatus 1according to an exemplary embodiment. FIG. 2 is a schematiccross-sectional view taken along line X-X′ of FIG. 1.

Referring to FIG. 1, the display apparatus 1 may include a display 10and a driver 20. The display 10 may include a plurality of pixels Pabove a substrate that are arranged in a matrix shape. The driver 20 mayinclude a scan driver applying a scan signal to a scan line connected toa pixel P and a data driver applying a data signal to a data line. Thedriver 20 may be provided in a non-display area of the substrate aroundthe display 10 where the pixels P are arranged. The driver 20 may be ina form of an integrated circuit (“IC”) chip to be directly disposed(e.g., mounted) above the substrate 10 where the display 10 is arranged,disposed (e.g., mounted) above a flexible printed circuit film, adheredonto the substrate in a form of a tape carrier package (“TCP”), ordirectly provided at the substrate.

Referring to FIG. 2, the display apparatus 1 according to an exemplaryembodiment may include a substrate 100, a light emitting diode (“LED”)200 above the substrate 100, an insulating layer 194 above the LED 200,and a wire grid polarizer (“WGP”) 300 above the insulating layer 194.

In an exemplary embodiment, the substrate 100 may include variousmaterials such as a glass material, a metallic material, or a plasticmaterial such as polyethyeleneterepthalate (“PET”), polyethyelenennapthalate (“PEN”), polyimide, etc.

A buffer layer 110 may be provided above the substrate 100. A thin filmtransistor TFT and the LED 200 may be provided above the buffer layer110.

The buffer layer 110 may prevent impure atoms from penetrating throughthe substrate 100 and may flatten a surface of the substrate 100. In anexemplary embodiment, the buffer layer 110 may include an inorganicmaterial, such as silicon nitride (SIN_(x)) and/or silicon oxide(SiO_(x)) in a single layer structure or a multilayer structure. Asemiconductor layer 120 may be located above the buffer layer 110.

A gate electrode 140 may be arranged in an upper portion of thesemiconductor layer 120. A source electrode 160 a and a drain electrode160 b may electrically communicate with each other according to a signalapplied to the gate electrode 140. In an exemplary embodiment, the gateelectrode 140 may include at least one of aluminum (Al), platinum (Pt),palladium (Pd), silver (Ag), magnesium (Mg), gold (Au), nickel (Ni),neodymium (Nd), iridium (Ir), chromium (Cr), lithium (Li), calcium (Ca),molybdenum (Mo), titanium (Ti), tungsten (W), and copper (Cu) in asingle layer structure or a multilayer structure in consideration ofadhesion with adjacent layers, planarization of surfaces of stackedlayers, processability, etc.

In this regard, to achieve insulation between the semiconductor layer120 and the gate electrode 140, a gate electrode layer 130 includingsilicon nitride SIN_(x) and/or silicon oxide SiO_(x) may be interposedbetween the semiconductor layer 120 and the gate electrode 140.

An interlayer insulating layer 150 may be provided above an upperportion of the gate electrode 140. In an exemplary embodiment, theinterlayer insulating layer 150 may include a material, such as siliconnitride (SIN_(x)) and/or silicon oxide (SiO_(x)) in a single layerstructure or a multilayer structure, for example.

The source electrode 160 a and the drain electrode 160 b may be arrangedin an upper portion of the interlayer insulating layer 150. The sourceelectrode 160 a and the drain electrode 160 b may be electricallyconnected to the semiconductor layer 120 through a contact hole definedin the interlayer insulating layer 150 and the gate insulating layer130. In an exemplary embodiment, the source electrode 160 a and thedrain electrode 160 b may include at least one of aluminum (Al),platinum (Pt), palladium (Pd), silver (Ag), magnesium (Mg), gold (Au),nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), lithium (Li),calcium (Ca), molybdenum (Mo), titanium (Ti), tungsten (W), and copper(Cu) in a single layer structure or a multilayer structure inconsideration of conductivity, etc., for example.

Although not shown, a protection layer (not shown) may be arranged tocover the thin film transistor TFT in order to protect the thin filmtransistor TFT having the structure described above. In an exemplaryembodiment, the protection layer may include, for example, an inorganicmaterial, such as silicon nitride (SIN_(x)), silicon oxide (SiO_(x)),and/or silicon nitrogen oxide (SiNOx).

A planarization layer 170 may be disposed above the substrate 100. Theplanarization layer 170 may generally flatten an upper surface of thethin film transistor TFT and protect the thin film transistor TFT andvarious devices when the LED 200 is arranged in an upper portion of thethin film transistor TFT. In an exemplary embodiment, the planarizationlayer 170 may include, for example, an acryl-based organic material or abenzocyclobutene (“BCB”), etc. In this regard, the buffer layer 110, thegate insulating layer 130, the interlayer insulating layer 150, and theplanarization layer 170 may be disposed on an entire surface of thesubstrate 100.

A pixel defining layer 180 may be arranged in an upper portion of thethin film transistor TFT. The pixel defining layer 180 may be locatedabove the planarization layer 170 and may include a concave region 180 adefining a pixel area. The concave region 180 a may expose a centralportion of a first electrode 190. The LED 200 may be disposed (e.g.,mounted) in the concave region 180 a.

In an exemplary embodiment, the pixel defining layer 180 may include,for example, an organic insulating layer. Examples of the organicinsulating material may include an acryl-based polymer, such aspolymethylmethacrylate (“PMMA”) or polystyrene (“PS”), a polymerderivative having a phenol-based group, an imide-based polymer, anarylether-based polymer, an amide-based polymer, a fluorine-basedpolymer, a p-xylene-based polymer, a vinyl alcohol-based polymer, and acombination thereof.

The first electrode 190 may be disposed above the planarization layer170. The first electrode 190 may be electrically connected to the thinfilm transistor TFT through a contact hole defined in the planarizationlayer 170. Although the first electrode 190 is connected to the drainelectrode 160 b of the thin film transistor TFT in FIG. 2, according toanother exemplary embodiment, the first electrode 190 may be connectedto the source electrode 160 a of the thin film transistor TFT. The firstelectrode 190 may expose a central portion through the concave region180 a provided in the pixel defining layer 180. The LED 200 may bedisposed (e.g., mounted) in the exposed central portion.

The first electrode 190 may be provided as a (semi)transparent electrodeor a reflective electrode. In an exemplary embodiment, when the firstelectrode 190 is provided as the (semi)transparent electrode, the firstelectrode 190 may include, for example, indium tin oxide (“ITO”), indiumzinc oxide (“IZO”), zinc oxide (ZnO), indium oxide (In₂O₃), indiumgallium oxide (“IGO”), or aluminum zinc oxide (“AZO”). In an exemplaryembodiment, when the first electrode 190 is provided as the reflectiveelectrode, the first electrode 190 may include, for example, areflection layer including Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, or acombination thereof, and a layer including ITO, IZO, ZnO, In₂O₃, IGO, orAZO. However, the invention is not limited thereto. The first electrode190 may include various other materials and may have variousmodifications such as a single layer structure or a multilayerstructure.

The LED 200 may be disposed above the first electrode 190. In anexemplary embodiment, the LED 200 may be a micro LED, for example. Inthis regard, the term ‘micro’ may indicate a size ranging from about 1micrometer (μm) to about 100 μm but the invention is not limitedthereto. The LED 200 may also be applied to an LED having a size greateror smaller than the micro size. A single LED 200 or a plurality of LEDs200 may be picked up on a wafer by a transfer tool and may betransferred to the substrate 100, and thus the LED 200 may beaccommodated in the concave region 180 a of the pixel defining layer 180above the substrate 100. In an exemplary embodiment, the LED 200 may bea red, green, blue, or white LED or an ultraviolet (“UV”) LED, forexample.

The LED 200 may include a p-n diode 250, a first contact electrode 210,and a second contact electrode 260. The first contact electrode 210and/or the second contact electrode 260 may include one or more layersand may include various conductive materials including a metal, aconductive oxide, and conductive polymers, for example. The firstcontact electrode 210 and the second contact electrode 260 mayselectively include a reflection layer, for example, a silver layer. Thefirst contact electrode 210 may be electrically connected to the firstelectrode 190. The second contact electrode 260 may be electricallyconnected to the WGP 300. The p-n diode 250 may include a lower p-dopinglayer 220, one or more quantum well layers 230, and an upper n-dopinglayer 240. In another exemplary embodiment, the upper doping layer 240may be a p-doping layer, and the lower doping layer 220 may be ann-doping layer. The p-n diode 250 may have a rectilinear side wall or adownwardly or upwardly tapered side wall.

An example of the LED 200 is illustrated as a vertical micro LED in FIG.2 but the invention is not limited thereto. In other exemplaryembodiments, the LED 200 may be a flip micro LED, a horizontal microLED, etc., in which the first contact electrode 210 and the secondcontact electrode 260 are arranged in the same direction. In this case,locations of the first electrode 190 and a second electrode (e.g., WGP300) may correspond to locations of the first contact electrode 210 andthe second contact electrode 260.

A reflection layer 192 may be interposed between the first electrode 190and the LED 200. The reflection layer 192 may partially cover thecentral portion of the first electrode 190 exposed through the concaveregion 180 a and side and upper surfaces of the pixel defining layer180. The reflection layer 192 may be arranged to cover the side surfacesof the pixel defining layer 180, i.e., the concave region 180 a, andhave a concave shape. Through the aforementioned structure, lightemitted from the LED 200 may be reflected from the reflection layer 192,thereby improving light extraction efficiency.

In an exemplary embodiment, the reflection layer 192 may function as areflection electrode, may include a reflection layer including, forexample, Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, or a combinationthereof, and may selectively further include a layer including ITO, IZO,ZnO, In₂O₃, IGO, or AZO. However, the invention is not limited thereto.The reflection layer 192 may include various materials and may havevarious modifications such as a single layer structure or a multilayerstructure.

The insulating layer 194 may surround the LED 200 inside the concaveregion 180 a of the pixel defining layer 180. The insulating layer 194may fill a space between the concave region 180 a of the pixel defininglayer 180 and the LED 200, thereby covering the concave region 180 a andthe reflection layer 192. The insulating layer 194 may include anorganic insulating material. In an exemplary embodiment, for example,the insulating layer 194 may include acryl, PMMA, BCB, polyimide,acrylate, epoxy, polyester, etc., but is not limited thereto. Theinsulating layer 194 may function to flatten an upper surface so thatthe WGP 300 may be arranged in an upper portion of the insulating layer194.

The insulating layer 194 may expose an upper surface 200 a of the LED200. In an exemplary embodiment, the insulating layer 194 may have aheight not to cover the second contact electrode 260 located in theupper surface 200 a of the LED 200 so that the second contact electrode260 may be exposed, for example. A height of the insulating layer 194may be equal to or less than a height of the LED 200 in order not tocover the second contact electrode 260 located in the upper surface 200a of the LED 200.

The WGP 300 may be arranged in an upper portion of the insulating layer194. The WGP 300 of the exemplary embodiment may be configured as aregular array of fine metal wires aligned in parallel. The WGP 300 mayperform the same function as a general polarizer but may have metalwires aligned at a gap below a wavelength of incident light withoutorientating a material forming the polarizer and may be advantageouslyeasy in terms of patterning. The WGP 300 may be arranged in the upperportion of the LED 200, thereby improving visibility that maydeteriorate due to reflection of external light.

The WGP 300 may be in direct contact with the second contact electrode260 of the LED 200 having the exposed upper surface 200 a that is notcovered by the insulating layer 194. The WGP 300 may be provided as thearray of fine metal wires so that the WGP 300 may be in direct contactwith the second contact electrode 260 of the LED 200 and may function asa common electrode. The WGP 300 may be located above an entire surfaceof the insulating layer 194 located in a display area. As describedabove, the WGP 300 may function as not only a polarizing layer but alsoas the common electrode by directly contacting the second contactelectrode 260 of the LED 200, and thus the WGP 300 may be in electricalcontact with an electrode power supply line outside the display area.

The WGP 300 described above may act as the common electrode, and thus aseparate common electrode is unnecessary, thereby simplifying a process.The WGP 300 may be provided as the array of the fine metal wires so thateach wire functions as a cooling pin, and thus the WGP 300 may functionto easily emit light and heat generated together from the LED 200 tooutside.

FIG. 3 is a cross-sectional view schematically illustrating a displayapparatus 2 according to another exemplary embodiment.

Referring to FIG. 3, the display apparatus 2 according to an exemplaryembodiment may include the substrate 100, the LED 200 above thesubstrate 100, the insulating layer 194 which is disposed above the LED200 and in which an open portion, i.e. an opening 194 a, exposing atleast a part of the upper surface 200 a of the LED 200 is defined, andthe WGP 300 above the insulating layer 194.

The display apparatus 2 according to an exemplary embodiment isdifferent from the display apparatus 1 described above in a structure ofthe insulating layer 194. A difference in the structure of theinsulating layer 194 will be described below and other configurations ofthe display apparatus 2 are the same as those of the display apparatus 1described above, and thus redundant descriptions thereof are omitted.

The insulating layer 194 may surround the LED 200 inside the concaveregion 180 a of the pixel defining layer 180. The insulating layer 194may fill a space between the concave region 180 a of the pixel defininglayer 180 and the LED 200, thereby covering the concave region 180 a andthe reflection layer 192. The insulating layer 194 may include anorganic insulating material. The insulating layer 194 may function toflatten an upper surface so that the WGP 300 may be arranged in an upperportion of the insulating layer 194.

The insulating layer 194 may expose the upper surface 200 a of the LED200. In an exemplary embodiment, the insulating layer 194 may have aheight greater than a height of the LED 200 with reference to thesubstrate 100, and the opening 194 a exposing the upper surface 200 a ofthe LED 200 may be defined in the insulating layer 194, for example, forexample. The opening 194 a of the insulating layer 194 may expose theupper surface 200 a of the LED 200 wholly or at least partially. In anexemplary embodiment, the second contact electrode 260 located in theupper surface 200 a of the LED 200 may be exposed by the opening 194 a,for example.

The WGP 300 may be arranged in an upper portion of the insulating layer194. The WGP 300 may be arranged in an upper portion of the LED 200,thereby improving visibility that may deteriorate due to reflection ofexternal light. The WGP 300 may be disposed above the upper surface 200a of the LED 200 exposed by the opening 194 a, and thus the WGP 300 maybe in direct contact with the second contact electrode 260 of the LED200. That is, the WGP 300 may be located above an entire surface of theinsulating layer 194 and may be in direct contact with the secondcontact electrode 260 of the LED 200, thereby functioning as a commonelectrode.

As described above, the WGP 300 may act as the common electrode, andthus a separate common electrode is unnecessary, thereby simplifying aprocess. The WGP 300 may be provided as an array of fine metal wires sothat each wire functions as a cooling pin, and thus the WGP 300 mayfunction to easily emit light and heat generated together by the LED 200to outside.

FIG. 4 is a cross-sectional view schematically illustrating a displayapparatus 3 according to another exemplary embodiment.

Referring to FIG. 4, the display apparatus 3 according to an exemplaryembodiment may include the substrate 100, the LED 200 above thesubstrate 100, the insulating layer 194 above the LED 200, the WGP 300above the insulating layer 194, and a pixel protection layer 410 and asecond electrode 500 interposed between the LED 200 and the insulatinglayer 194.

A structure of the LED 200 of the display apparatus 3 according to anexemplary embodiment is the same as that of the display apparatus 1 ofFIG. 2, and thus a redundant description thereof is omitted.

The LED 200 may be disposed above the reflection layer 192. In anexemplary embodiment, the LED 200 may be a micro LED, for example. Inthis regard, the term ‘micro’ may indicate a size ranging from about 1μm to about 100 μm but the invention is not limited thereto. The LED 200may also be applied to an LED having a size greater or smaller than themicro size. A single LED 200 or a plurality of LEDs 200 may be picked upon a wafer by a transfer tool and may be transferred to the substrate100, and thus the LED 200 may be accommodated in the concave region 180a of the pixel defining layer 180 above the substrate 100. In anexemplary embodiment, the LED 200 may be a red, green, blue, or whiteLED or an UV LED, for example.

The pixel protection layer 410 may be further disposed above the LED200. The pixel protection layer 410 may surround the LED 200 inside theconcave region 180 a of the pixel defining layer 180. The pixelprotection layer 410 may fill a space between the concave region 180 aof the pixel defining layer 180 and the LED 200, thereby covering theconcave region 180 a and the reflection layer 192. The pixel protectionlayer 410 may include an organic insulating material. An upper surfaceof the pixel protection layer 410 may be generally flat but may be, forexample, curved. The pixel protection layer 410 may cover the reflectionlayer 192 including all patterned side surfaces. The reflection layer192 may function as an auxiliary electrode, and thus the pixelprotection layer 410 may wholly cover the reflection layer 192, therebypreventing a short with the second electrode 500 that will be describedlater.

The pixel protection layer 410 may include a plurality of fine particles420 that may function to scatter and diffuse light emitted in the LED200. The fine particles 420 may be single particles and core-shell typeparticles. The fine particles 420 may include a light reflectionmaterial or a light scattering material, for example, an organicmaterial such as transparent resin, an inorganic material such as aglass material or a silicon compound, metal or a combination thereof. Inan exemplary embodiment, when the fine particles 420 include transparentresin, the fine particles 420 may include, for example, one of PMMA,polysterene, polyurethane, epoxy, and silicon resin.

The pixel protection layer 410 may expose the upper surface 200 a of theLED 200. In an exemplary embodiment, the pixel protection layer 410 mayhave a height greater than a height of the LED 200 with reference to thesubstrate 100, and an open portion exposing the upper surface 200 a ofthe LED 200, i.e., an opening 410 a, may be defined in the pixelprotection layer 410, for example. The opening 410 a, as shown in FIG.4, may expose an upper surface of the LED 200, i.e., at least a part ofthe second contact electrode 260, through an upper surface of the pixelprotection layer 410 having an inwardly sunken shape, the pixelprotection layer 410 having a height greater than the height of the LED200 with reference to the substrate 100. In another exemplaryembodiment, the height of the upper surface of the pixel protectionlayer 410 may be equal to the height of the LED 200 with reference tothe substrate 100 so that at least a part of the second contactelectrode 260 may be exposed to outside.

The opening 410 a of the pixel protection layer 410 may expose the uppersurface 200 a of the LED 200 wholly or at least partially. In anexemplary embodiment, the second contact electrode 260 located in theupper surface 200 a of the LED 200 exposed by the opening 410 a may beexposed, for example. Although a height of the pixel protection layer410 is greater than the height of the upper surface 200 a of the LED 200with reference to the substrate 100, and the upper surface 200 a of theLED 200 is exposed through the opening 410 a in FIG. 4, according toanother exemplary embodiment, the height of the pixel protection layer410 may be equal to or less than the upper surface 200 a of the LED 200with reference to the substrate 100, and the upper surface 200 a of theLED 200 may be exposed.

The second electrode 500 may be disposed above the pixel protectionlayer 410. The second electrode 500 may be arranged in an entire surfaceof the substrate 100 as a common electrode. The second electrode 500 maycontact the LED 200 through the opening 410 a of the pixel protectionlayer 410 that exposes at least a part of the upper surface 200 a of theLED 200. In an exemplary embodiment, the second contact electrode 260may be located in the upper surface 200 a of the LED 200 and may beelectrically connected to the second contact electrode 260 of the LED200 through the opening 410 a of the pixel protection layer 410, forexample.

The second electrode 500 may be provided as a (semi)transparentelectrode or a reflective electrode. In an exemplary embodiment, whenthe second electrode 500 is provided as the (semi)transparent electrode,the second electrode 500 may include a layer including metal having asmall work function, i.e., Li, Ca, LiF/Ca, LiF/Al, Ag, Mg, and acombination thereof and a (semi)transparent conductive layer includingITO, IZO, ZnO or In₂O₃. In an exemplary embodiment, when the secondelectrode 500 is provided as the reflective electrode, the secondelectrode 500 may include the layer including Li, Ca, LiF/Ca, LiF/Al,Ag, Mg, and a combination thereof, for example. The configuration andmaterial of the second electrode 500 are not limited thereto and mayvary in various ways.

The insulating layer 194 may be disposed above the second electrode 500.The insulating layer 194 may cover the second electrode 500, mayinsulate the second electrode 500 and the WGP 300 that will be describedlater, and simultaneously, may flatten an upper surface so that the WGP300 may be arranged thereabove. The insulating layer 194 may include anorganic insulating material.

The WGP 300 may be arranged in an upper portion of the insulating layer194. The WGP 300 of the exemplary embodiment may be configured as aregular array of fine metal wires aligned in parallel. The WGP 300 mayperform the same function as a general polarizer but may align metalwires at a gap below a wavelength of incident light without orientatinga material forming the polarizer and may be advantageously easy topatterning. The WGP 300 may be arranged in the upper portion of the LED200, thereby improving visibility that deteriorates due to reflection ofexternal light.

The WGP 300 may be provided as the array of the fine metal wires so thateach wire functions as a cooling pin, and thus the WGP 300 may functionto easily emit light and heat generated together from the LED 200 tooutside.

FIG. 5 is a cross-sectional view schematically illustrating a displayapparatus 4 according to another exemplary embodiment.

Referring to FIG. 5, the display apparatus 4 according to an exemplaryembodiment may include the substrate 100, the LED 200 above thesubstrate 100, a first electrode 190 a and a second electrode 190 b thatare electrically connected to the LED 200, the insulating layer 194above the LED 200, and the WGP 300 above the insulating layer 194.

Structures of the thin film transistor TFT and the planarization layer170 covering the thin film transistor TFT of the display apparatus 4according to the exemplary embodiment are the same as those of thedisplay apparatus 1 of FIG. 2, and thus redundant descriptions thereofare omitted.

The first electrode 190 a and the second electrode 190 b may be disposedabove the planarization layer 170. The first electrode 190 a may beelectrically connected to the thin film transistor TFT through a contacthole defined in the planarization layer 170. The second electrode 190 bmay be arranged in one side of the first electrode 190 a. In theexemplary embodiment, the first electrode 190 a and the second electrode190 b may be arranged at the same layer. In an exemplary embodiment, thefirst electrode 190 a and the second electrode 190 b may be disposedabove the planarization layer 170, for example. Here, the firstelectrode 190 a and the second electrode 190 b arranged at the samelayer may mean the first electrode 190 a and the second electrode 190 belectrically connected to the LED 200 in the same side. When the firstelectrode 190 a and the second electrode 190 b are arranged at the samelayer, the LED 200 may be a flip LED or a horizontal LED in which afirst contact electrode and a second contact electrode are arranged inthe same direction.

The first electrode 190 a and the second electrode 190 b may be providedas (semi)transparent electrodes or reflective electrodes. In anexemplary embodiment, when the first electrode 190 a and the secondelectrode 190 b are provided as the (semi)transparent electrodes, thefirst electrode 190 a and the second electrode 190 b may include, forexample, ITO, IZO, ZnO, In₂O₃, IGO, or AZO. In an exemplary embodiment,when the first electrode 190 a and the second electrode 190 b areprovided as the reflective electrodes, the first electrode 190 a and thesecond electrode 190 b may include reflection layers including Ag, Mg,Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, or a combination thereof, and layersincluding ITO, IZO, ZnO, In₂O₃, IGO, or AZO. However, the invention isnot limited thereto. The first electrode 190 a and the second electrode190 b may include various other materials and have various modificationssuch as a single layer structure or a multilayer structure.

The pixel defining layer 180 may be disposed above the thin filmtransistor TFT. The pixel defining layer 180 may be located above theplanarization layer 170 and may include the concave region 180 adefining a pixel area. The concave region 180 a may expose at least apart of the first electrode 190 a and at least a part of the secondelectrode 190 b. The LED 200 may be disposed (e.g., mounted) in theconcave region 180 a. In an exemplary embodiment, the pixel defininglayer 180 may include, for example, an organic insulating layer.

The LED 200 may be disposed above the first electrode 190 a and thesecond electrode 190 b. In an exemplary embodiment, the LED 200 may be amicro LED, for example. In this regard, the term ‘micro’ may indicate asize ranging from about 1 μm to about 100 μm but the invention is notlimited thereto. The LED 200 may also be applied to an LED having a sizegreater or smaller than the micro size. A single LED 200 or a pluralityof LEDs 200 may be picked up on a wafer by a transfer tool and may betransferred to the substrate 100, and thus the LED 200 may beaccommodated in the concave region 180 a of the pixel defining layer 180above the substrate 100. In an exemplary embodiment, the LED 200 may bea red, green, blue, or white LED or an UV LED, for example.

The LED 200 may include a p-n diode (not shown), a first contactelectrode (not shown), and a second contact electrode (not shown). Thefirst contact electrode and/or the second contact electrode may includeone or more layers and may include various conductive materialsincluding metal, a conductive oxide, and conductive polymers. In anexemplary embodiment, the first contact electrode and the second contactelectrode may selectively include the reflection layer 192 (refer toFIGS. 2, 3 and 4), for example, a silver layer. The first contactelectrode may be electrically connected to the first electrode 190 a.The second contact electrode may be electrically connected to the secondelectrode 190 b. The p-n diode may include a p-doping layer of one sidethereof, one or more quantum well layer, and an n-doping layer ofanother side thereof.

In the exemplary embodiment, the LED 200 may be a flip micro LED, ahorizontal micro LED, etc., in which the first contact electrode and thesecond contact electrode are arranged in the same direction. In thiscase, locations of the first electrode 190 a and the second electrode190 b may correspond to locations of the first contact electrode and thesecond contact electrode.

The LED 200 may have an upper surface, a lower surface, and a sidesurface 200 b connecting the upper surface and the lower surface. Ametal layer 270 may be arranged to cover the side surface 200 b of theLED 200. The metal layer 270 may surround the side surface 200 b of theLED 200 as shown in FIG. 5 and may cover only a part of the side surface200 b according to another exemplary embodiment. Although not shown, aninsulating layer may be interposed between the side surface 200 b of theLED 200 and the metal layer 270 to electrically insulate the p-n diodeand the metal layer 270. Through the aforementioned structure, lightemitted from the LED 200 may be reflected from the metal layer 270,thereby improving light extraction efficiency. The first and secondcontact electrodes 210 a and 210 b may connect the first and secondelectrodes 190 a and 190 b, respectively, to the LED 200.

In an exemplary embodiment, the metal layer 270 may include a reflectionlayer including, for example, Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, ora combination thereof, and may selectively further include a layerincluding ITO, IZO, ZnO, In₂O₃, IGO, or AZO. However, the invention isnot limited thereto. The metal layer 270 may include various materialsand may have various modifications such as a single layer structure or amultilayer structure.

The insulating layer 194 may surround the LED 200 inside the concaveregion 180 a of the pixel defining layer 180. The insulating layer 194may fill a space between the concave region 180 a of the pixel defininglayer 180 and the LED 200, thereby covering the concave region 180 a andthe reflection layer 192. In an exemplary embodiment, the insulatinglayer 194 may include an organic insulating material, for example. In anexemplary embodiment, for example, the insulating layer 194 may includeacryl, PMMA, BCB, polyimide, acrylate, epoxy, polyester, etc., but isnot limited thereto. The insulating layer 194 may cover the uppersurface 200 a of the LED 200 to flatten an upper surface so that the WGP300 may be arranged in an upper portion of the insulating layer 194.

The WGP 300 may be arranged in an upper portion of the insulating layer194. The WGP 300 of the exemplary embodiment may be configured as aregular array of fine metal wires aligned in parallel. The WGP 300 mayperform the same function as a general polarizer but may align metalwires at a gap below a wavelength of incident light without orientatinga material forming the polarizer and may be advantageously easy topatterning. The WGP 300 may be arranged in the upper portion of the LED200, thereby improving visibility that deteriorates due to reflection ofexternal light.

The WGP 300 may be provided as the array of the fine metal wires so thateach wire functions as a cooling pin, and thus the WGP 300 may functionto easily emit light and heat generated together from the LED 200 tooutside.

As described above, according to one or more exemplary embodiments, adisplay apparatus having improved reliability and visibility may beimplemented. However, the scope of the invention is not limited to theeffect.

It should be understood that exemplary embodiments described hereinshould be considered in a descriptive sense only and not for purposes oflimitation. Descriptions of features within each exemplary embodimentshould typically be considered as available for other similar featuresin other exemplary embodiments.

While one or more exemplary embodiments have been described withreference to the figures, it will be understood by those of ordinaryskill in the art that various changes in form and details may be madetherein without departing from the spirit and scope as defined by thefollowing claims.

What is claimed is:
 1. A display apparatus comprising: a substrate; alight-emitting diode disposed above the substrate; an insulating layerdisposed above the light-emitting diode; and a wire grid polarizerdisposed above the insulating layer.
 2. The display apparatus of claim1, wherein the insulating layer exposes an upper surface of thelight-emitting diode.
 3. The display apparatus of claim 2, wherein thewire grid polarizer contacts the upper surface of the light-emittingdiode.
 4. The display apparatus of claim 2, wherein a height of an uppersurface of the insulating layer is equal to or less than a height of theupper surface of the light-emitting diode with reference to thesubstrate.
 5. The display apparatus of claim 2, wherein an opening whichexposes the upper surface of the light-emitting diode is defined in theinsulating layer.
 6. The display apparatus of claim 2, wherein thelight-emitting diode comprises a p-n diode, a first contact electrode,and a second contact electrode, wherein the first contact electrode andthe second contact electrode are disposed in the upper surface of thelight-emitting diode.
 7. The display apparatus of claim 1, furthercomprising: a first electrode disposed above the substrate; and areflection layer interposed between the light-emitting diode and thefirst electrode.
 8. The display apparatus of claim 7, furthercomprising: a pixel defining layer comprising a concave region whichexposes a central portion of the first electrode, wherein the reflectionlayer is disposed above the concave region.
 9. The display apparatus ofclaim 7, further comprising: a pixel protection layer disposed above thelight-emitting diode.
 10. The display apparatus of claim 9, wherein thepixel protection layer covers the reflection layer.
 11. The displayapparatus of claim 9, wherein the pixel protection layer furthercomprises fine particles.
 12. The display apparatus of claim 9, furthercomprising: a second electrode disposed above the pixel protectionlayer, wherein an opening which exposes at least a part of the uppersurface of the light-emitting diode is defined in the pixel protectionlayer, and wherein the second electrode contacts at least a part of theupper surface of the light-emitting diode through the opening.
 13. Thedisplay apparatus of claim 1, further comprising: a first electrode anda second electrode disposed above a same layer of the substrate, whereinthe light-emitting diode is electrically connected to the firstelectrode and the second electrode.
 14. The display apparatus of claim13, wherein the light-emitting diode comprises an upper surface, a lowersurface, and a side surface connecting the upper surface and the lowersurface and further comprises a metal layer disposed to cover the sidesurface of the light-emitting diode.
 15. The display apparatus of claim13, wherein the light-emitting diode comprises a p-n diode, a firstcontact electrode, and a second contact electrode, wherein the firstcontact electrode and the second contact electrode are disposed in asame side.
 16. The display apparatus of claim 1, further comprising: athin film transistor disposed above the substrate and comprising asemiconductor layer, a gate electrode, a source electrode, and a drainelectrode.
 17. A display apparatus comprising: a substrate; a thin filmtransistor disposed above the substrate; a first electrode electricallyconnected to the thin film transistor; a light-emitting diode disposedabove the first electrode and comprising a first contact electrodeelectrically connected to the first electrode and a second contactelectrode spaced apart from the first contact electrode at apredetermined gap; an insulating layer which covers at least a part ofthe light-emitting diode; and a wire grid polarizer disposed above theinsulating layer.
 18. The display apparatus of claim 17, wherein theinsulating layer comprises an open portion which exposes at least a partof the second contact electrode.
 19. The display apparatus of claim 18,wherein the second contact electrode and the wire grid polarizer are incontact with each other through the open portion.
 20. The displayapparatus of claim 17, further comprising: a pixel protection layerwhich covers the first electrode and the light-emitting diode and inwhich an open portion which exposes at least a part of the secondcontact electrode is defined; and a second electrode spaced apart fromthe first electrode and electrically connected to the second contactelectrode through the open portion.